Splicing tape application device with rigid electrostatic charge eliminator

ABSTRACT

The invention is in the field of devices enabling the sticking of splicing tapes to the ends of strips put into rolls, to prevent their later unwinding. The present invention relates to a device ( 1 ) for applying splicing tapes ( 22 ) on a strip ( 30 ) made of flexible material. The device ( 1 ) is equipped with a passive device ( 50 ) enabling the elimination of the electrostatic forces that disturb the operation of the device. The device ( 1 ) according to the invention is mainly used on photographic film or paper slitters.

FIELD OF THE INVENTION

The present invention is in the field of devices that enable thesticking of splicing tapes onto other strips usually made of flexiblematerial. These devices must operate correctly, and especially not causesticking faults due to electrostatic phenomena. More specifically, theinvention is in the field of automatic devices for sticking splicingtape onto the strands of the ends of strips forming rolls or reels ofphotographic films or papers; with the sticking process intended toprevent the strips from unwinding, just after they have been cut on aslitter.

BACKGROUND OF THE INVENTION

The use of slitters is universally known in the photographic industry.Slitters enable the simultaneous cutting into several strips with presetwidths of a wider strip or axis of film or paper previously coated witha photosensitive emulsion layer. The wider strip to be cut has aprogrammed length itself. The cut strips obtained from the wider stripare wound around a central core. Each of the rolls thus obtained endswith a free strand. The free strand is intended to take a pre-gluedsplicing tape of flexible material, to fix this free strand of the stripend onto its roll, in order to prevent the roll from unwinding duringlater manipulations or operations in the process, in particular duringthe operation of packaging the rolls and transport of the rolls. Thesplicing tape is applied to the roll using an automatic sticking device,attached to an annexed part of the slitter. This sticking deviceautomatically places and sticks the splicing tapes onto the free strandsof the respective rolls. Before the sticking operation of the splicingtapes to the roll, they are previously unstuck or separated from asupport strip. The unsticking generates electrostatic forces that causequality faults, because the separated splicing tape is deviated from itsplanned path towards the free strand of the strip end to be stuck.Therefore, it does not stick the free strand onto its roll. In additionthe deviated splicing tape is often found, for example, inside thesticking device and disturbs its operation It is an object of thepresent invention to eliminate the effect of electrostatic forces insticking devices used on slitters.

The principle enabling electrostatic forces to be eliminated is wellknown to those skilled in the art. It includes using ionization of theair. To eliminate electrostatic forces, passive induction means,comprising points linked to ground for example are used, as described inPatent EP 708,580.

SUMMARY OF THE INVENTION

The present invention relates to a splicing tape sticking or applicationdevice equipped with a passive means that enables the elimination of theelectrostatic forces that disturb the operation of the device as far asstopping the operation. Stopping the operation of the sticking devicecauses the slitter to stop; these stops generate significantproductivity losses that the device according to the inventioneliminates.

The present invention relates to a device for applying precut splicingtapes initially attached successively to a first strip serving assupport made of flexible material, onto a second strip made of flexiblematerial of the roll end, by successively separating the splicing tapesof the first strip. The device comprises a frame in which are arrangedthe means for unwinding, winding, guiding, and mechanical tension checkof the first strip, and a pressure part that enables the splicing tapeseparated from the first strip to be applied to the second strip of theroll end when the roll is approached by the pressure part. The device ischaracterized in that it further comprises a passive means ofelectrostatic discharge acting by the electrical field effect andattached to one of the device's guiding means. The passive means has itsend placed in the sticking zone just before the intersection of thepaths of the separated slicing tape and the second strip to be stuck, asclose as possible to the path of the separated slicing tape withouttouching the tape, and without touching the second strip to be stuck, soas to generate the electrostatic discharge of the zone and preventattraction of the separated tape by the pressure means.

Other advantages and characteristics of the present invention willappear in the following description and more particularly in a preferredembodiment of the invention illustrated in the following figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents a diagram of the device according to the invention;

FIG. 2 represents a splicing tape and its support used in the deviceaccording to the invention;

FIG. 3 represents cross-section 3-3 of FIG. 2;

FIG. 4 represents the operation of a device which does not comprise themeans according to the invention; and

FIG. 5 represents the operation of the device according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description refers to a preferred embodiment ofthe invention; this with reference to the drawings of the above figures,wherein the same reference numbers identify the same parts for each ofthe various figures.

FIG. 1 represents a diagram of the device 1 according to the invention.It is attached, for example, on a slitter for photographic film or paperusing a slide 2 and a locking means 3. The slide 2 is, for example,dovetail shape and the locking means 3 is a device comprising a shaftand cam lever. The device 1 enables the application and sticking ofsplicing tapes 22 onto the free strand 30 of a roll 32 of strips ofphotographic film or paper having a preset width, so that the freestrand 30 is fixed onto the roll 32 (FIGS. 4 and 5). The application ofthe splicing tapes 22 by the device 1 onto the roll 32 prevents the roll32 from unwinding during later operations or handling. It iscontemplated to attach to the slitter several devices 1 for applyingsplicing tapes according to the invention, i.e. one device per cut stripon the machine, which enables the simultaneous sticking of the freestrands 30 of each of the corresponding rolls 32. The device 1 comprisesa frame 4 in which are arranged various means that enable the storageand running of a strip 20. The means of the device 1 are respectively anunwinder means or device 5 of the strip 20, a guide or guiding means 6,7, 8, 9, 10, 11, 12, 18, a mechanical tension checker or mechanicaltension check means 15 of the strip 20, a winder or winding means ordevice 17 of the strip 20 and an applicator or means 19 that enablesapplication and pressing of the splicing tape 22 separated from thestrip 20 onto the free strand 30. According to a preferred embodiment ofthe invention, the unwinding 5 and winding 17 means are rotating metalcylinders. The means 15 enables checking of the tension of the strip 20during its unwinding from the cylinder 5. The means 15 is, for example,a preset mechanical device attached to the shaft of the cylinder 5; thisdevice brakes the cylinder 5 during unwinding, so as to maintain anappropriate tension opposed to the unwinding of the strip 20. Duringoperation of the device 1, this tension stays less than the windingtension of the cylinder 17. Guiding means 6, 7, 8, 9, 10, are rotatingcylinders made of plastic, for example PVC; the means 18 and 19 are forexample rotating metal cylinders not coated or coated with polyurethaneor neoprene. The guiding means 11 and 12 are flat guiding parts attachedto the frame 4; these guiding means 11 and 12 comprise adjacent planesurfaces 11P and 12P that enable holding of the strip 20 and separationof the splicing tape 22 from the strip 20 at 11D. According to apreferred embodiment, the flat guide 11 and the flat guide 12 are metal,in order to provide good electrical conduction. While in anotherembodiment, the flat guide 12 can be for example metalized Teflon.

The device 1 enables a roll 23 of strip 20 to be automatically unwound.FIG. 2 represents the strip 20 whose essential part is a support strip21 coated with a fine layer of solid saturated hydrocarbons 26. On thesupport 21 splicing tapes 22 precut into pre-glued adhesive foils areplaced one following the other. The layer of hydrocarbons 26 enables thetapes 22 to stick to the support strip 21. The splicing tape 22comprises at least one pre-glued zone 24 and one zone without glue 25,as shown in FIGS. 2 and 3. The pre-glued zone 24 is on the side oppositethe support 21. The strip 20 is for example a roll of wax paper 21 onwhich are arranged at regular intervals thin precut splicing tapes 22made of plastic. The device 1 according to the invention unwinds fromthe roll 23, the strip 20 comprising the support strip 21 which isusually paper and on which are set the splicing tapes 22. As shown inFIGS. 4 and 5, the strip 20 comes to the outlet of the device 1 in theflat guides 11 and 12 zone following the path D1. When part of the strip20 supporting the splicing tapes 22 comes to the break line 11D formingthe end of the flat extended guide 11, the strip 22 is folded back tofollow the path D2. At 11D, by the break generated by the shape of theflat guide 11, the splicing tape 22 is unstuck from its support 21 andby inertia follows the path D3, to go between the pressure cylinder 19and the free strand 30 of the roll 32. The roll 32 has been placed closeto the pressure cylinder 19 by a not shown means attached to theslitter. In the 11D zone, the unsticking of the splicing tape 22 fromits support 21 generates significant electrostatic forces.

According to the splicing tapes 22 used, and in particular according totheir surface area, the surface density of the corresponding charge isvariable. For example, for splicing tapes with a surface area of 11square centimeters (1.8 cm by 6.3 cm) intended to stick the free strand30 of a roll of photographic paper 32, the surface density of theaverage charge is approximately 1.4 nanocoulomb per square centimeter.The electrostatic forces generated by the unsticking of the splicingtape 22 from its support 21 and the friction of the support 21 of thestrip 20 on the flat guide 11 have the effect of attracting the splicingtape 22 to the rotating pressure cylinder 19 as shown in FIG. 4. Despitethe glued zone 24 provided to stick the slicing tape 22 onto the roll 32and the force exerted by the pressure cylinder 19, the resultingelectrostatic force is large enough for the splicing tape not to stickto the roll 32, and stay attracted by the cylinder 19. The consequenceof this phenomenon is on the one hand not sticking to the free strand 30on the roll 32 and on the other hand accumulating the splicing tapes 22on the cylinder 19. The secondary consequences are unwanted separationsof the stuck tapes, for example, one with another and which are foundeverywhere in bunches in the device 1 or around it, or even accumulateand contaminate the roll 32. The electrostatic charge created whenunsticking the splicing tape 22 generates a matching charge on thepressure cylinder 19. The charge on the cylinder 19, by the metal natureof the cylinder 19 and because the radius of curvature of the cylinder19 is less than the radius of curvature of the roll 32, is greater thanthe charge of the same sign created on the roll 32. In addition, as thecharge on the splicing tape 22 that is not electrically very conductiveis of the opposite sign to that of the pressure cylinder 19, the tape 22is attracted by the cylinder 19 which exerts an attraction force greaterthan that of the roll 32. The charge on the splicing tape 22 that is notelectrically very conductive persists in time, i.e. the relaxation timeenabling the tape 22 to fully discharge the electricity is about severaltens of seconds after the unsticking. Whereas the application process ofa splicing tape 22 using the device 1 only lasts a few seconds; thus theembodiment corresponding to FIG. 4 systematically generates the problemsmentioned above.

The device according to the invention includes using a simple and robustmeans 50 in the device 1 to eliminate the interfering electrostaticforces generated by the unsticking of the splicing tape 22 at 11D. Themeans 50, used in the invention, is a “passive” means of electrostaticdischarge in the sense that it does not include or use an energy source.The means 50 acts by electrical field effect and by its low radius ofcurvature; it enables charges matching those generated on the splicingtape 22 to concentrate at its end 51 placed in the sticking zone 52. Theelectrical field has sufficiently high intensity to reach a valuegreater than or equal to the ionization potential of the ambient air inthe sticking zone 52. The air zone thus ionized is made electricallyconductive. The sticking zone 52 is thus practically discharged and theresulting charge on the splicing tape 22 is no longer enough for thetape 22 to be attracted by the pressure cylinder 19.

According to a preferred embodiment of this invention, this means 50 isa very thin metal foil, attached to the concave top part 12C of theguide 12 with fixing means enabling the foil 50 of the guide 12 to notbe electrically insulated. The thickness of the foil is between 0.05 mmand 0.10 mm. In a preferred embodiment of the invention the thickness ofthe foil is 0.06 mm. The guide 12 in combination with the extended flatguide 11 ensures the guiding of the strip 21 carrying the splicing tapes22. For this purpose the guides 11 and 12 comprise adjacent planesurfaces 11P and 12P. The emerging length 51 of the foil 50 in relationto the guide 12 is situated in the ionized air zone 52, just before theline of intersection Li of the paths of the splicing tape 22 and thestrip 30 of the roll 32. The emerging length 51 is adjusted to not makecontact with the roll 32, while being situated as close as possible tothe path D1, D3 of the splicing tape 22. Thus positioned, the foil 50enables electrostatic discharge of the tape 22 separated or unstuck fromits support 21, which prevents the separated tape 22 from beingattracted by the rotating cylinder 19. In a preferred embodiment, thefoil 50 is supported by the metal guide 12, to ensure electricalcontinuity of the assembly to ground through the frame 4 of the device1. In the zone to be discharged the uniformity of electrostaticdischarge using the foil 50 is better than using for example a point.

While the invention has been described in detail and with reference to apreferred embodiment it will be apparent that all changes andmodifications of this preferred embodiment leading to other embodimentswithin the spirit and scope of the claims should be considered asequivalent and integrated in the present application.

1. A device for applying precut splicing tapes 3 initially attached successively to a first strip serving as support made of flexible material, onto a second strip made of flexible material of an end of a roll, by successively separating the splicing tapes from the first strip, said device comprising: a frame in which are arranged an unwinding device, a winding device, a guide, and a mechanical tension checker of the first strip, a pressure part enabling the splicing tape separated from the first strip to be applied to a second strip of the end of the roll when said roll is approached by the pressure part; a passive device of electrostatic discharge acting by an electrical field effect and attached to one of the guides of the device, said passive device having an end placed in a sticking zone just before an intersection of paths of the separated slicing tape and the second strip to be stuck, as close as possible to the path of the separated slicing tape without touching said tape, and without touching the second strip to be stuck, so as to generate the electrostatic discharge of the sticking zone and prevent attraction of the separated tape by the pressure part.
 2. A device according to claim 1, wherein the passive device of electrostatic discharge is an electrically conductive foil.
 3. A device according to claim 2, wherein a thickness of the foil is between 0.05 mm and 0.10 mm.
 4. A device according to claim 3, wherein a preferred thickness of the foil is 0.06 mm.
 5. A device according to claim 1, wherein the first support strip made of flexible material is a paper strip coated with a thin layer of solid saturated hydrocarbons.
 6. A device according to claim 1, wherein the splicing tapes pre-glued and fixed successively to the first support strip comprise at least one pre-glued zone on the side opposite the support strip.
 7. A device according to claim 1, wherein the second strip of flexible material is a photographic paper strip. 